Light sensitive composition and light sensitive planographic printing plate precursor

ABSTRACT

Disclosed are a light sensitive composition containing A) an addition polymerizable ethylenically double bond-containing monomer, B) a photopolymerization initiator, and C) a polymer binder, wherein the addition polymerizable ethylenically double bond-containing monomer is a reaction product of a tertiary amine having two or more hydroxyl groups in the molecule, a diisocyanate having an aromatic ring in the molecule and a compound having a hydroxyl group and an addition polymerizable ethylenically double bond in the molecule, and a light sensitive planographic printing plate precursor comprising the light sensitive composition.

FIELD OF THE INVENTION

[0001] The present invention relates to a light sensitive compositionand a light sensitive planographic printing plate precursor, andparticularly to a light sensitive composition and a light sensitiveplanographic printing plate precursor, each providing high sensitivity,high storage stability, and high printing durability.

BACKGROUND OF THE INVENTION

[0002] A planographic printing plate is obtained by imagewise exposing aplanographic printing plate precursor to harden exposed portions,dissolving the non-exposed portions of the exposed precursor with adeveloper, washing the resulting precursor with water, and finisher gumtreating the washed precursor. Recently, a method has been studied inwhich a planographic printing plate precursor is digitally exposed basedon image information employing laser ray, and developed with a developerto form an image with high resolution and high sharpness. As oneembodiment, there is a system manufacturing a planographic printingplate in which a light sensitive planographic printing plate precursoris scanning exposed employing a light source modulated with an imagesignal transmitted by communication line or output signal from anelectronic plate making system or an image processing system.

[0003] However, a conventional planographic printing plate precursoremploying a diazo resin has problem in that spectral sensitization tosuit a wavelength of laser ray and obtain high sensitivity is difficult.

[0004] Recently, a planographic printing plate precursor comprising aphotopolymerizable light sensitive layer containing aphotopolymerization initiator has been noted as a printing plateprecursor for digital exposure employing a laser light, since it ispossible to provide a photopolymerizable light sensitive layer highlysensitive to the laser light. A printing plate precursor for CTP(Computer to Plate) system recording digital data employing such a laserlight is required to be more highly light-sensitive for the purpose ofcarrying out recording in a short time.

[0005] The planographic printing plate precursor is said to be suitablefor forming an image with high sensitivity which comprises aphotopolymerizable light sensitive layer containing aphotopolymerization initiator, since the photopolymerization initiatorimagewise generates radicals on imagewise exposure, and the resultingradicals cause radical chain polymerization as radical initiatingspecies.

[0006] In order to attain high sensitivity, various methods have been sofar proposed. For example, a method is proposed in Japanese PatentO.P.I. Publication Nos. 63-277653, 63-260909, 1-105238, and 1-203413 inwhich a tertiary amino group is incorporated in a monomer (an additionpolymerizable ethylenically unsaturated monomer). However, methodsproposed so far do not provide satisfactory sensitivity or printingdurability, and has problem in that when a light sensitive planographicprinting plate precursor employing these methods is stored for a longtime, its sensitivity is lowered.

SUMMARY OF THE INVENTION

[0007] The present invention has been made in view of the above. Anobject of the invention is to provide a light sensitive composition anda light sensitive planographic printing plate precursor, each providinghigh sensitivity, high storage stability, and high printing durability.

DETAILED EXPLANATION OF THE INVENTION

[0008] The above objects of the invention can be attained by thefollowings:

[0009] 1-1. A light sensitive composition containing A) an additionpolymerizable ethylenically double bond-containing monomer, B) aphotopolymerization initiator, and C) a polymer binder, wherein theaddition polymerizable ethylenically double bond-containing monomer is areaction product of a tertiary amine having two or more hydroxyl groupsin the molecule, a diisocyanate having an aromatic ring in the moleculeand a compound having a hydroxyl group and an addition polymerizableethylenically double bond in the molecule. 1-2. The light sensitivecomposition of item 1-1 above, wherein the photopolymerization initiatoris a polyhalogenated methyl group-containing triazine compound.

[0010]1-3. The light sensitive composition of item 1-1 above, whereinthe tertiary amine has a hydroxyl group of from 2 to 6 in the molecule.

[0011] 1-4. The light sensitive composition of item 1-1 above, whereinthe polymer binder is a copolymer of a carboxyl group-containing monomerand an alkyl methacrylate or alkyl acrylate.

[0012] 1-5. The light sensitive composition of item 1-4 above, whereinthe carboxyl group-containing monomer is acrylic acid or methacrylicacid.

[0013] 1-6. A light sensitive planographic printing plate precursorcomprising a support and provided thereon, a photopolymerizable lightsensitive layer containing A) an addition polymerizable ethylenicallydouble bond-containing monomer, B) a photopolymerization initiator, andC) a polymer binder, wherein the addition polymerizable ethylenicallydouble bond-containing monomer is a reaction product of a tertiary aminehaving two or more hydroxyl groups in the molecule, a diisocyanatehaving an aromatic ring in the molecule and a compound having a hydroxylgroup and an addition polymerizable ethylenically double bond in themolecule.

[0014]1-7. The light sensitive planographic printing plate precursor ofitem 1-6 above, wherein the photopolymerization initiator is apolyhalogenated methyl group-containing triazine compound.

[0015] 1-8. The light sensitive planographic printing plate precursor ofitem 1-6 above, wherein the tertiary amine has a hydroxyl group of from2 to 6 in the molecule.

[0016] 1-9. The light sensitive planographic printing plate precursor ofitem 1-6 above, wherein the polymer binder is a copolymer of a carboxylgroup-containing monomer and an alkyl methacrylate or alkyl acrylate.

[0017] 1-10. The light sensitive planographic printing plate precursorof item 1-9 above, wherein the carboxyl group-containing monomer isacrylic acid or methacrylic acid.

[0018] 2-1. A light sensitive composition containing A) an additionpolymerizable ethylenically double bond-containing monomer, B) aphotopolymerization initiator, and C) a polymer binder, wherein theaddition polymerizable ethylenically double bond-containing monomer is areaction product of a polyhydric alcohol having a tertiary amino groupin the molecule, an aromatic diisocyanate and a compound having ahydroxyl group and an addition polymerizable ethylenically double bondin the molecule.

[0019]2-2. The light sensitive composition of item 2-1 above, containinga triazine having a polyhalogenated methyl group.

[0020] 2-3. A planographic printing plate precursor comprising a supportand provided thereon, a layer containing A) an addition polymerizableethylenically double bond-containing monomer, B) a photopolymerizationinitiator, and C) a polymer binder, wherein the addition polymerizableethylenically double bond-containing monomer is a reaction product of apolyhydric alcohol having a tertiary amino group in the molecule, anaromatic diisocyanate and a compound having a hydroxyl group and anaddition polymerizable ethylenically double bond in the molecule.

[0021] 2-4. The planographic printing plate precursor of item 2-3 above,wherein the layer contains a triazine having a polyhalogenated methylgroup.

[0022] The present inventor has made an extensive study in view of theabove. As a result, the inventor has found that a light sensitivecomposition provides high sensitivity which contains A) an additionpolymerizable ethylenically double bond-containing monomer, B) aphotopolymerization initiator, and C) a polymer binder, wherein theaddition polymerizable ethylenically double bond-containing monomer is areaction product of a tertiary amine having two or more hydroxyl groupsin the molecule, a diisocyanate having an aromatic ring in the moleculeand a compound having a hydroxyl group and an addition polymerizableethylenically double bond in the molecule, and a planographic printingplate precursor comprising the light sensitive composition provide highstorage stability regarding sensitivity, and high printing durability,and has completed the invention.

[0023] The light sensitive composition of the invention will beexplained below.

[0024] The light sensitive composition of the invention contains, asmain components, A) a reaction product of a tertiary amine having two ormore hydroxyl groups in the molecule, a diisocyanate having an aromaticring in the molecule, and a compound having a hydroxyl group and anaddition polymerizable ethylenically double bond in the molecule as anaddition polymerizable ethylenically double bond-containing monomer, B)a photopolymerization initiator, and C) a polymer binder.

[0025] The addition polymerizable ethylenically double bond-containingmonomer will be explained below. The addition polymerizableethylenically double bond-containing monomer (hereinafter also referredto as the addition polymerizable ethylenically double bond-containingmonomer in the invention) is a reaction product of a tertiary aminehaving two or more hydroxyl groups in the molecule, a diisocyanatehaving an aromatic ring in the molecule and a compound having a hydroxylgroup and an addition polymerizable ethylenically double bond in themolecule

[0026] The tertiary amine having two or more hydroxyl groups in themolecule has a hydroxyl group of preferably from 2 to 6, and morepreferably from 2 to 4. Examples of the tertiary amine having two ormore hydroxyl groups in the molecule include triethanolamine,N-methyldiethanolamine, N-ethyldiethanolamine, N-ethyldiethanolamine,N-n-butyldiethanolamine, N-tert-butyldiethanolamine,N,N-di(hydroxyethyl)aniline,N,N,N′,N′-tetra-2-hydroxypropylethylenediamine, p-tolyldiethanolamine,N,N, N′, N′-tetra-2-hydroxyethylethylenediamine,N,N-bis(2-hydroxypropyl)aniline, allyldiethanolamine,3-dimethylamino-1,2-propane diol, 3-diethylamino-1,2-propane diol,N,N-di(n-propylamino)-2,3-propane diol,N,N-di(iso-propylamino)-2,3-propane diol, and3-(N-methyl-N-benzylamino)-1,2-propane diol, but the invention is notspecifically limited thereto.

[0027] Examples of the diisocyanate having an aromatic ring in themolecule include 1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate,1,4-phenylene diisocyanate, tolylene-2,4-diisocyanate,tolylene-2,5-diisocyanate, tolylene-2,6-diisocyanate,1,3-(diisocyanatomethyl)benzene, 4,4′-(diisocyanatomethyl)biphenyl,1,3-bis(1-isocyanato-1-methyl-ethyl)benzene, anddi(4-isocyanatophenyl)methane, but the invention is not specificallylimited thereto.

[0028] Examples of the compound having a hydroxyl group and an additionpolymerizable ethylenically double bond in the molecule include thefollowing compounds MH-1 through MH-13, but the invention is notspecifically limited thereto.

[0029] The reaction product of a tertiary amine having two or morehydroxyl groups in the molecule, a diisocyanate having an aromatic ringin the molecule and a compound having a hydroxyl group and an additionpolymerizable ethylenically double bond in the molecule, can besynthesized according to the same method as a conventional method inwhich a urethaneacrylate compound is ordinarily synthesized employing adiol, a diisocyanate and an acrylate having a hydroxyl group.

[0030] Examples of the reaction product of a tertiary amine having twoor more hydroxyl groups in the molecule, a diisocyanate having anaromatic ring in the molecule and a compound having a hydroxyl group andan addition polymerizable ethylenically double bond in the molecule willbe listed below, but the invention is not specifically limited thereto.

[0031] M-1: A reaction product of triethanolamine (1 mole),1,4-phenylene diisocyanate (3 moles), and Exemplified Compound MH-1 (3moles)

[0032] M-2: A reaction product of triethanolamine (1 mole),tolylene-2,4-diisocyanate (3 moles), and Exemplified Compound MH-2 (3moles)

[0033] M-3: A reaction product of N-ethyldiethanolamine (1 mole),tolylene-2,4-diisocyanate (2 moles), and Exemplified Compound MH-2 (2moles)

[0034] M-4: A reaction product of triethanolamine (1 mole),tolylene-2,4-diisocyanate (2 moles), and Exemplified Compound MH-8 (2moles)

[0035] M-5: A reaction product of N-n-butyldiethanolamine (1 mole),1,4-phenylene diisocyanate (2 moles), and Exemplified Compound MH-7 (2moles)

[0036] M-6: A reaction product of tolyldiethanolamine (1 mole),tolylene-2,4-diisocyanate (2 moles), and Exemplified Compound MH-11 (2moles)

[0037] M-7: A reaction product of 3-diethylamino-1,2-propanediol (1mole), tolylene-2,4-diisocyanate (2 moles), and Exemplified CompoundMH-12 (2 moles)

[0038] The content of the addition polymerizable ethylenically doublebond-containing monomer in the invention in the light sensitivecomposition is from 3 to 80% by weight, and preferably from 5 to 60% byweight based on the solid components of the composition.

[0039] The addition polymerizable ethylenically double bond-containingmonomer in the invention may be mixed with other addition polymerizableethylenically double bond-containing monomers. The other additionpolymerizable ethylenically double bond-containing monomers are notspecifically limited, but preferred examples thereof include an acrylatesuch as 2-ethylhexyl acrylate, 2-hydroxypropyl acrylate, glycerolacrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate,nonylphenoxyethyl acrylate, tetrahydrofurfuryl-oxyethyl acrylate,tetrahydrofurfuryloxyhexanorideacrylate; a methacrylate, itaconate,crotonate or maleate alternative of the above acrylate; a bifunctionalacrylate such as ethyleneglycol diacrylate, triethyleneglycoldiacrylate, pentaerythritol diacrylate, hydroquinone diacrylate,resorcin diacrylate, hexanediol diacrylate, neopentyl glycol diacrylate,tripropylene glycol diacrylate, hydroxypivalic acid neopentyl glycoldiacrylate, neopentyl glycol adipate diacrylate, diacrylate ofhydroxypivalic acid neopentyl glycol-ε-caprolactone adduct,2-(2-hydroxy-1,1-dimethylethyl)-5-hydroxymethyl-5-ethyl-1,3-dioxanediacrylate, tricyclodecanedimethylol acrylate, tricyclodecanedimethylolacrylate-εcaprolactone adduct or 1,6-hexanediol diglycidyletherdiacrylate; a dimethacrylate, diitaconate, dicrotonate or dimaleatealternative of the above diacrylate; a polyfunctional acrylate such astrimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate,trimethylolethane triacrylate, pentaerythritol triacrylate,pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate,dipentaerythritol pentaacrylate, dipentaerythritol hexacrylate,dipentaerythritol hexacrylate-ε-caprolactone adduct, pyrrogalloltriacrylate, propionic acid dipentaerythritol triacrylate, propionicacid dipentaerythritol tetraacrylate or hydroxypivalylaldehyde modifieddimethylolpropane triacrylate; a methacrylate, itaconate, crotonate ormaleate alternative of the above polyfunctional acrylate.

[0040] A prepolymer can be used, and examples of the prepolymer includecompounds as described later. The prepolymer with a photopolymerizableproperty, which is obtained by incorporating acrylic acid or methacrylicin an oligomer with an appropriate molecular weight, can be suitablyemployed. This prepolymer can be used singly, as an admixture of theabove described monomers and/or oligomers.

[0041] Examples of the prepolymer include polyester (meth)acrylateobtained by incorporating (meth)acrylic acid in a polyester of apolybasic acid such as adipic acid, trimellitic acid, maleic acid,phthalic acid, terephthalic acid, hymic acid, malonic acid, succinicacid, glutaric acid, itaconic acid, pyromellitic acid, fumalic acid,pimelic acid, sebatic acid, dodecanic acid or tetrahydrophthalic acidwith a polyol such as ethylene glycol, ethylene glycol, diethyleneglycol, propylene oxide, 1,4-butane diol, triethylene glycol,tetraethylene glycol, polyethylene glycol, grycerin, trimethylolpropane, pentaerythritol, sorbitol, 1,6-hexanediol or 1,2,6-hexanetriol;an epoxyacrylate such as bisphenol A•epichlorhydrin•(meth)acrylic acidor phenol novolak•epichlorhydrin•(meth)acrylic acid obtained byincorporating (meth)acrylic acid in an epoxy resin; an urethaneacrylatesuch as ethylene glycol•adipicacid•tolylenediisocyanate•2-hydroxyethylacrylate, polyethyleneglycol•tolylenediisocyanate•2-hydroxyethylacrylate, hydroxyethylphthalylmethacrylate•xylenediisocyanate,1,2-polybutadieneglycol•tolylenediisocyanate-2-hydroxyethylacrylate ortrimethylolpropane•propyleneglycol•tolylenediisocyanate•2-hydroxyethylacrylate, obtained byincorporating (meth)acrylic acid in an urethane resin; a siliconeacrylate such as polysiloxane acrylate, orpolysiloxane•diisocyanate•2-hydroxyethylacrylate; an alkyd modifiedacrylate obtained by incorporating a methacroyl group in an oil modifiedalkyd resin; and a spiran resin acrylate.

[0042] The light sensitive composition of the invention may contain amonomer such as a phosphazene monomer, triethylene glycol, an EOmodified isocyanuric acid diacrylate, an EO modified isocyanuric acidtriacrylate, dimethyloltricyclodecane diacrylate, trimethylolpropaneacrylate benzoate, an alkylene glycol acrylate, or a urethane modifiedacrylate, or an addition polymerizable oligomer or prepolymer having astructural unit derived from the above monomer.

[0043] The ethylenic monomer usable in the invention is preferably aphosphate compound having at least one (meth)acryloyl group. Thephosphate compound is a compound having a (meth)acryloyl group in whichat least one hydroxyl group of phosphoric acid is esterified, and thephosphate compound is not limited as long as it has a (meth)acryloylgroup.

[0044] Besides the above compounds, compounds disclosed in JapanesePatent O.P.I. Publication Nos. 58-212994, 61-6649, 62-46688, 62-48589,62-173295, 62-187092, 63-67189, and 1-244891, compounds described onpages 286 to 294 of “11290 Chemical Compounds” edited by KagakukogyoNipposha, and compounds described on pages 11 to 65 of “UV•EB KokaHandbook (Materials)” edited by Kobunshi Kankokai can be suitably used.Of these compounds, compounds having two or more acryl or methacrylgroups in the molecule are preferable, and those having a molecularweight of not more than 10,000, and preferably not more than 5,000 aremore preferable.

[0045] The content of the other addition polymerizable ethylenicallydouble bond-containing monomer optionally mixed with the additionpolymerizable ethylenically double bond-containing monomer in theinvention in the light sensitive composition is not more than 20 times,and preferably not more than 10 times that of the addition polymerizableethylenically double bond-containing monomer in the invention.

[0046] A photopolymerization initiator will be explained below.

[0047] The photopolymerization initiators capable of being used in theinvention include carbonyl compounds, organic sulfur compounds,peroxides, redox compounds, azo or diazo compounds, halides andphoto-reducing dyes disclosed in J. Kosar, “Light Sensitive Systems”,Paragraph 5. The examples thereof are disclosed in British Patent No.1,459,563.

[0048] Examples of the photopolymerization initiators include thefollowing compounds:

[0049] A benzoin derivative such as benzoin methyl ether, benzoini-propyl ether, or α,α-dimethoxy-α-phenylacetophenone; a benzophenonederivative such as benzophenone, 2,4-dichlorobenzophenone, o-benzoylmethyl benzoate, or 4,4′-bis (dimethylamino) benzophenone; athioxanthone derivative such as 2-chlorothioxanthone,2-1-propylthioxanthone; an anthraquinone derivative such as2-chloroanthraquinone or 2-methylanthraquinone; an acridone derivativesuch as N-methylacridone or N-butylacridone; α,α-diethoxyacetophenone;benzil; fluorenone; xanthone; an uranyl compound; a triazine derivativedisclosed in Japanese Patent Publication Nos. 59-1281 and 61-9621 andJapanese Patent O.P.I. Publication No. 60-60104; an organic peroxidecompound disclosed in Japanese Patent O.P.I. Publication Nos. 59-1504and 61-243807; a diazonium compound in Japanese Patent Publication Nos.43-23684, 44-6413, 47-1604 and U.S. Pat. No. 3,567,453; an organic azidecompound disclosed in U.S. Pat. Nos. 2,848,328, 2,852,379 and 2,940,853;orthoquinondiazide compounds disclosed in Japanese Patent PublicationNos. 36-22062b, 37-13109, 38-18015 and 45-9610; various onium compoundsdisclosed in Japanese Patent Publication No. 55-39162, Japanese PatentO.P.I. Publication No. 59-14023 and “Macromolecules”, Volume 10, p. 1307(1977); azo compounds disclosed in Japanese Patent Publication No.59-142205; metal arene complexes disclosed in Japanese Patent O.P.I.Publication No. 1-54440, European Patent Nos. 109,851 and 126,712, and“Journal of Imaging Science”, Volume 30, p. 174 (1986); (oxo) sulfoniumorganoboron complexes disclosed in Japanese Patent O.P.I. PublicationNos. 5-213861 and 5-255347; titanocenes disclosed in Japanese PatentO.P.I. Publication Nos. 59-152396 and 61-151197; transition metalcomplexes containing a transition metal such as ruthenium disclosed in“Coordination Chemistry Review”, Volume 84, p. 85-277 (1988) andJapanese Patent O.P.I. Publication No. 2-182701; 2,4,5-triarylimidazoldimmer disclosed in Japanese Patent O.P.I. Publication No. 3-209477;carbon tetrabromide; organic halide compounds disclosed in JapanesePatent O.P.I. Publication No. 59-107344; triarylmonoalkylborate ammoniumsalts; and iron-arene complexes.

[0050] Preferred photopolymerization initiator is a titanocene compound.Examples of the titanocene compound includedi-cyclopentadienyl-Ti-dichloride, dicyclopentadienyl-Ti-bisphenyl,dicyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophenyl,dicyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophenyl,dicyclopentadienyl-Ti-bis-2,4,6-trifluorophenyl,dicyclopentadienyl-Ti-bis-2,6-difluorophenyl,dicyclopentadienyl-Ti-bis-2,4-difluorophenyl,di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophenyl,di-methylcyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophenyl,di-methylcyclopentadienyl-Ti-bis-2,4-difluorophenyl, and bis(cyclopentadienyl)-bis (2,6-difluoro-3-(pyrryl)phenyl) titanium(IRUGACURE 784, produced by Ciba Specialty Co., Ltd.), but are notlimited thereto.

[0051] In the invention, especially preferred photopolymerizationinitiator is a polyhalogenated methyl group-containing triazinecompound.

[0052] As the polyhalogenated methyl group-containing triazine compoundis preferred a 1,3,5-triazine having a trichloromethyl group or adichloromethyl group at least one thereof.

[0053] Examples of the polyhalogenated methyl group-containing triazinecompound will be listed below, but the invention is not specificallylimited thereto. R = CCl₃ R = CHCl₂

TA-1 TB-1

TA-2 TB-2

TA-3 TB-3

TA-4 TB-4

TA-5 TB-5

TA-6 TB-6

TA-7 TB-7

TA-8 TB-8

TA-9 TB-9

TA-10 TB-10

TA-11 TB-11

TA-12 TB-12

TA-13 TB-13

TA-14 TB-14

TA-15 TB-15

TA-16 TB-16

[0054] When a laser is employed as a light source, the light sensitivecomposition of the invention preferably contains a sensitizing dye. Thesensitizing dye is preferably a dye having an absorption maximum in thewavelength of light emitted from the light source or its vicinity.

[0055] Examples of the sensitizing dyes, which can induce sensitivity tothe wavelengths of visible to near infrared regions, include cyanines,phthalocyanines, merocyanines, porphyrins, Spiro compounds, ferrocenes,fluorenes, fulgides, imidazoles, perylenes, phenazines, phenothiazines,polyenes, azo compounds, diphenylmethanes, triphenylmethanes,polymethine acridines, cumarines, ketocumarines, quinacridones, indigos,styryl dyes, pyrylium dyes, pyrromethene dyes, pyrazolotriazolecompounds, benzothiazole compounds, barbituric acid derivatives,thiobarbituric acid derivatives, ketoalcohol borate complexes, andcompounds disclosed in European Patent No. 568,993, U.S. Pat. Nos.4,508,811 and 5,227,227, and Japanese Patent O.P.I. Publication Nos.2001-125255 and 11-271969.

[0056] Examples in which the above polymerization initiators are used incombination with the sensitizing dye are disclosed in Japanese PatentO.P.I. Publication Nos. 2001-125255 and 11-271969.

[0057] The content of the photopolymerization initiator is notspecifically limited but is preferably from 0.1 to 20 parts by weightbased on 100 parts by weight of addition polymerizable ethylenicallydouble bond-containing monomer in the light sensitive composition. Thecontent ration of the sensitizing dye to the photopolymerizationinitiator in the light sensitive composition is preferably from 1:100 to100:1 by mol.

[0058] The light sensitive composition of the invention contains apolymer binder.

[0059] As the polymer binder can be used a polyacrylate resin, apolyvinylbutyral resin, a polyurethane resin, a polyamide resin, apolyester resin, an epoxy resin, a phenol resin, a polycarbonate resin,a polyvinyl butyral resin, a polyvinyl formal resin, a shellac resin, oranother natural resin. These resins can be used as an admixture of twoor more thereof.

[0060] The polymer binder used in the invention is preferably a vinylcopolymer obtained by copolymerization of an acryl monomer, and morepreferably a copolymer containing (a) a carboxyl group-containingmonomer unit and (b) an alkyl methacrylate or alkyl acrylate unit as thecopolymerization component.

[0061] Examples of the carboxyl group-containing monomer include anα,β-unsaturated carboxylic acid, for example, acrylic acid, methacrylicacid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydrideor a carboxylic acid such as a half ester of phthalic acid with2-hydroxymethacrylic acid.

[0062] Examples of the alkyl methacrylate or alkyl acrylate include anunsubstituted alkyl ester such as methylmethacrylate, ethylmethacrylate,propylmethacrylate, butylmethacrylate, amylmethacrylate,hexylmethacrylate, heptylmethacrylate, octylmethacrylate,nonylmethacrylate, decylmethacrylate, undecylmethacrylate,dodecylmethacrylate, methylacrylate, ethylacrylate, propylacrylate,butylacrylate, amylacrylate, hexylacrylate, heptylacrylate,octylacrylate, nonylacrylate, decylacrylate, undecylacrylate, ordodecylacrylate; a cyclic alkyl ester such as cyclohexyl methacrylate orcyclohexyl acrylate; and a substituted alkyl ester such as benzylmethacrylate, 2-chloroethyl methacrylate, N,N-dimethylaminoethylmethacrylate, glycidyl methacrylate, benzyl acrylate, 2-chloroethylacrylate, N,N-dimethylaminoethyl acrylate or glycidyl acrylate.

[0063] The polymer binder in the invention can further contain, asanother monomer unit, a monomer unit derived from the monomer describedin the following items (1) through (14):

[0064] (1) A monomer having an aromatic hydroxy group, for example, o-,(p- or m-) hydroxystyrene, or o-, (p- or m-) hydroxyphenylacrylate;

[0065] (2) A monomer having an aliphatic hydroxy group, for example,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate,N-methylolacrylamide, N-methylolmethacrylamide, 4-hydroxybutyl acrylate,4-hydroxybutyl methacrylate, 5-hydroxypentyl acrylate, 5-hydroxypentylmethacrylate, 6-hydroxyhexyl acrylate, 6-hydroxyhexyl methacrylate,N-(2-hydroxyethyl)acrylamide, N-(2-hydroxyethyl)methacrylamide, orhydroxyethyl vinyl ether;

[0066] (3) A monomer having an aminosulfonyl group, for example, m- orp-aminosulfonylphenyl methacrylate, m- or p-aminosulfonylphenylacrylate, N-(p-aminosulfonylphenyl) methacrylamide, orN-(p-aminosulfonylphenyl)acrylamide;

[0067] (4) A monomer having a sulfonamido group, for example,N-(p-toluenesulfonyl)acrylamide, orN-(p-toluenesulfonyl)-methacrylamide;

[0068] (5) An acrylamide or methacrylamide, for example, acrylamide,methacrylamide, N-ethylacrylamide, N-hexylacrylamide,N-cyclohexylacrylamide, N-phenylacrylamide, N-nitrophenylacrylamide,N-ethyl-N-phenylacrylamide, N-4-hydroxyphenylacrylamide, orN-4-hydroxyphenylmethacrylamide;

[0069] (6) A monomer having a fluorinated alkyl group, for example,trifluoromethyl acrylate, trifluoromethyl methacrylate,tetrafluoropropyl methacrylate, hexafluoropropyl methacrylate,octafluoropentyl acrylate, octafluoropentyl methacrylate,heptadecafluorodecyl methacrylate, heptadecafluorodecyl methacrylate, orN-butyl-N-(2-acryloxyethyl)heptadecafluorooctylsulfonamide;

[0070] (7) A vinyl ether, for example, ethyl vinyl ether, 2-chloroethylvinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether,or phenyl vinyl ether;

[0071] (8) A vinyl ester, for example, vinyl acetate, vinylchroloacetate, vinyl butyrate, or vinyl benzoate;

[0072] (9) A styrene, for example, styrene, methylstyrene, orchloromethystyrene;

[0073] (10) A vinyl ketone, for example, methyl vinyl ketone, ethylvinyl ketone, propyl vinyl ketone, or phenyl vinyl ketone;

[0074] (11) An olefin, for example, ethylene, propylene, isobutylene,butadiene, or isoprene;

[0075] (12) N-vinylpyrrolidone, N-vinylcarbazole, or N-vinylpyridine,

[0076] (13) A monomer having a cyano group, for example, acrylonitrile,methacrylonitrile, 2-pentenenitrile, 2-methyl-3-butene nitrile,2-cyanoethyl acrylate, or o-, m- or p-cyanostyrene;

[0077] (14) A monomer having an amino group, for example,N,N-diethylaminoethyl methacrylate, N,N-dimethylaminoethyl acrylate,N,N-dimethylaminoethyl methacrylate, polybutadiene urethane acrylate,N,N-dimethylaminopropyl acrylamide, N,N-dimethylacrylamide,acryloylmorpholine, N-isopropylacrylamide, or N,N-diethylacrylamide.

[0078] Further another monomer may be copolymerized with the abovemonomer. As the polymer binder is also preferred an unsaturatedbond-containing copolymer which is obtained by reacting a carboxyl groupcontained in the above vinyl copolymer molecule with for example, acompound having a (meth)acryloyl group and an epoxy group. Examples ofthe compound having a (meth)acryloyl group and an epoxy group in themolecule include glycidyl acrylate, glycidyl methacrylate and an epoxygroup-containing unsaturated compound disclosed in Japanese PatentO.P.I. Publication No. 11-27196.

[0079] The weight average molecular weight of the above copolymer ispreferably 10,000 to 200,000 measured by gel permeation chromatography(GPC), but is not limited thereto.

[0080] The content of the polymer binder in the light sensitivecomposition is preferably from 10 to 90% by weight, more preferably from15 to 70% by weight, and still more preferably from 20 to 50% by weight,based on the solid content of the light sensitive composition, in viewof sensitivity.

[0081] The acid value of the polymer binder is preferably from 10 to150, more preferably from 30 to 120, and still more preferably from 50to 90, in view of balance of polarity of the photopolymerizable lightsensitive layer, which can prevent coagulation of pigment used in thephotopolymerizable light sensitive layer coating liquid.

[0082] The dry thickness of the photopolymerizable light sensitive layeris preferably 0.3 to 5 g/m², and more preferably 0.5 to 3 g/m².

[0083] The light sensitive composition of the invention preferablycontains a polymerization inhibitor in addition to the compoundsdescribed above, in order to prevent undesired polymerization of theethylenically double bond-containing monomer during the manufacture orstorage of a light sensitive planographic printing plate employing thecomposition. Examples of the polymerization inhibitor includehydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrrogallol,t-butylcatechol, benzoquinone, 4,4′-thiobis (3-methyl-6-t-butylphenol),2,2′-methylenebis (4-methyl-6-t-butylphenol),N-nitrosophenylhydroxylamine cerous salt, and2-t-butyl-6-(3-t-butyl-6-hydroxy-5-mrthylbenzyl)-4-methylphenylacrylate.

[0084] The polymerization inhibitor content is preferably 0.01 to 5% byweight based on the total solid content of the photopolymerizable lightsensitive layer composition. Further, in order to prevent polymerizationinduced by oxygen, a higher fatty acid such as behenic acid or a higherfatty acid derivative such as behenic amide may be added to the layer,or may be localized on the surface of the layer in the drying step aftercoating. The higher fatty acid or higher fatty acid derivative contentis preferably 0.5 to 10% by weight based on the total solid content ofthe photopolymerizable light sensitive layer composition.

[0085] A colorant can be also used. As the colorant can be used knownmaterials including commercially available materials. Examples of thecolorant include those described in revised edition “Ganryo Binran”,edited by Nippon Ganryo Gijutu Kyoukai (publishe by SeibunndouSinkosha), or “Color Index Binran”.

[0086] Kinds of the pigment include black pigment, yellow pigment, redpigment, brown pigment, violet pigment, blue pigment, green pigment,fluorescent pigment, and metal powder pigment. Examples of the pigmentinclude inorganic pigment (such as titanium dioxide, carbon black,graphite, zinc oxide, Prussian blue, cadmium sulfide, iron oxide, orchromate of lead, zinc, barium or calcium); and organic pigment (such asazo pigment, thioindigo pigment, anthraquinone pigment, anthanthronepigment, triphenedioxazine pigment, vat dye pigment, phthalocyaninepigment or its derivative, or quinacridone pigment).

[0087] Among these pigment, pigment is preferably used which does notsubstantially have absorption in the absorption wavelength regions of aspectral sensitizing dye used according to a laser for exposure. Theabsorption of the pigment used is not more than 0.05, obtained from thereflection spectrum of the pigment measured employing an integratingsphere and employing light with the wavelength of the laser used. Thepigment content is preferably 0.1 to 10% by weight, and more preferably0.2 to 5% by weight, based on the total solid content of thephotopolymerizable light sensitive layer composition.

[0088] When an argon laser (488 nm) or an SHG-YAG laser (532 nm) is usedas a light source for exposure, violet pigment or blue pigment ispreferably used in view of the above absorption wavelength relationshipor image visibility after the exposure. Such pigment examples includeCobalt Blue, cerulean blue, alkali blue lake, Victria Blue lake, metalfree phthalocyanine, Phthalocyanine Blue, Fast Sky Blue, IndanthreneBlue, indigo, dioxane violet, isoviolanthrone violet, Indanthrone Blue,and Indanthrene BC. Among these, Phthalocyanine Blue and dioxane violetare preferred.

[0089] The above composition can contain other additives such as asurfactant as a coatability improving agent, or an inorganic filler or aplasticizer for improving a physical property of the photopolymerizablelight sensitive layer, as long as performance of the invention is notjeopardized. The surfactant is preferably a fluorine-containedsurfactant.

[0090] Examples of the plasticizer include dioctyl phthalate, dimethylphthalate or tricresyl phosphate. The content of the other additives ispreferably not more than 10% by weight, based on the total solid contentof the composition.

[0091] The light sensitive planographic printing plate precursor of theinvention is obtained by preparing a coating liquid in which thephotopolymerizable light sensitive composition is dissolved in asolvent, coating the coating liquid on a support described later to forma photopolymerizable light sensitive layer on the support.

[0092] The thickness of the photopolymerizable light sensitive layer ispreferably from 0.3 to 10 g/m², and more preferably from 0.6 to 6 g/m².

[0093] The solvents used in the preparation of the coating liquid forthe photopolymerizable light sensitive layer in the invention include analcohol such as sec-butanol, isobutanol, n-hexanol, or benzyl alcohol; apolyhydric alcohol such as diethylene glycol, triethylene glycol,tetraethylene glycol, or 1,5-pentanediol; an ether such as propyleneglycol monobutyl ether, dipropylene glycol monomethyl ether, ortripropylene glycol monomethyl ether; a ketone or aldehyde such asdiacetone alcohol, cyclohexanone, or methyl cyclohexanone; and an estersuch as ethyl lactate, butyl lactate, diethyl oxalate, or methylbenzoate.

[0094] The prepared coating liquid for the photopolymerizable lightsensitive layer is coated on the support according to a conventionalmethod, and dried to obtain a light sensitive planographic printingplate precursor. Examples of the coating method include an air doctorcoating method, a blade coating method, a wire bar coating method, aknife coating method, a dip coating method, a reverse roll coatingmethod, a gravure coating method, a cast coating method, a curtaincoating method, and an extrusion coating method.

[0095] A low drying temperature of the coated photopolymerizable lightsensitive layer cannot provide sufficient printing durability, while tooa high drying temperature of the coated photopolymerizable lightsensitive layer results in marangoni and produces fog at non-imageportions. The drying temperature is preferably from 60 to 160° C., morepreferably from 80 to 140° C., and still more preferably from 90 to 120°C.

[0096] A protective layer is preferably provided on thephotopolymerizable light sensitive layer of the light sensitiveplanographic printing plate precursor of the invention. It is preferredthat the protective layer (oxygen shielding layer) is highly soluble ina developer (generally an alkaline solution) described later. Polyvinylalcohol or polyvinyl pyrrolidone is preferably used in the protectivelayer. Polyvinyl alcohol has the effect of preventing oxygen fromtransmitting and polyvinyl pyrrolidone has the effect of increasingadhesion between the oxygen shielding layer and the photopolymerizablelight sensitive layer adjacent thereto.

[0097] Besides the above two polymers, the oxygen shielding layer maycontain a water soluble polymer such as polysaccharide, polyethyleneglycol, gelatin, glue, casein, hydroxyethyl cellulose, carboxymethylcellulose, methyl cellulose, hydroxyethyl starch, gum arabic, sucroseoctacetate, ammonium alginate, sodium alginate, polyvinyl amine,polyethylene oxide, polystyrene sulfonic acid, polyacrylic acid, or awater soluble polyamide.

[0098] In the light sensitive planographic printing plate precursor ofthe invention, adhesive strength between the oxygen shielding layer andthe photopolymerizable light sensitive layer is preferably not less than35 mN/mm, and more preferably not less than 75 mN/mm. Preferredcomposition of the protective layer is disclosed in Japanese PatentO.P.I. Publication No. 10-10742.

[0099] The adhesive strength in the invention can be measured accordingto the following procedure.

[0100] When an adhesive tape with sufficient adhesive strength having apredetermined width is adhered onto the oxygen shielding layer, and thenpeeled at an angle of 90° to the plane of the light sensitiveplanographic printing plate precursor, strength necessary to peel theoxygen shielding layer from the photopolymerizable light sensitive layeris measured as the adhesive strength.

[0101] The protective layer may further contain a surfactant or amatting agent. The protective layer is formed, coating on thephotopolymerizable light sensitive layer a coating liquid in which theabove protective layer composition is dissolved in an appropriatecoating solvent, and drying. The main solvent of the coating solvent ispreferably water or an alcohol solvent such as methanol, ethanol, oriso-propanol.

[0102] The thickness of the protective layer is preferably 0.1 to 5.0μm, and more preferably 0.5 to 3.0 μm.

[0103] A support used in the light sensitive planographic printing plateprecursor of the invention has a hydrophilic surface.

[0104] Examples of the support include a plate of a metal such asaluminum, stainless steel, chromium, or nickel, a plastic film such as apolyester film, a polyethylene film or a polypropylene film which isdeposited or laminated with the above-described metal, and a polyesterfilm, a polyvinyl chloride film or a nylon film whose surface issubjected to hydrophilization treatment. Among the above, the aluminumplate is preferably used, and may be a pure aluminum plate or analuminum alloy plate.

[0105] As the aluminum alloy, there can be used various ones includingan alloy of aluminum and a metal such as silicon, copper, manganese,magnesium, chromium, zinc, lead, bismuth, nickel, titanium, sodium oriron.

[0106] It is preferable that the support in the invention is subjectedto degreasing treatment for removing rolling oil prior to surfaceroughening (graining). The degreasing treatments include degreasingtreatment employing solvents such as trichlene and thinner, and anemulsion degreasing treatment employing an emulsion such as kerosene ortriethanol. It is also possible to use an aqueous alkali solution suchas caustic soda for the degreasing treatment. When an aqueous alkalisolution such as caustic soda is used for the degreasing treatment, itis possible to remove soils and an oxidized film which can not beremoved by the above-mentioned degreasing treatment alone. When anaqueous alkali solution such as caustic soda is used for the degreasingtreatment, the resulting support is preferably subjected to desmuttreatment in an aqueous solution of an acid such as phosphoric acid,nitric acid, sulfuric acid, chromic acid, or a mixture thereof, sincesmut is produced on the surface of the support. The surface rougheningmethods include a mechanical surface roughening method and anelectrolytic surface roughening method electrolytically etching thesupport surface.

[0107] Though there is no restriction for the mechanical surfaceroughening method, a brushing roughening method and a honing rougheningmethod are preferable. The brushing roughening method is carried out byrubbing the surface of the support with a rotating brush with a brushhair with a diameter of 0.2 to 0.8 mm, while supplying slurry in whichvolcanic ash particles with a particle size of 10 to 100 μm aredispersed in water to the surface of the support. The honing rougheningmethod is carried out by ejecting obliquely slurry with pressure appliedfrom nozzles to the surface of the support, the slurry containingvolcanic ash particles with a particle size of 10 to 100 μm dispersed inwater. A surface roughening can be also carried out by laminating asupport surface with a sheet on the surface of which abrading particleswith a particle size of from 10 to 100 μm was coated at intervals of 100to 200 μm and at a density of 2.5×10³ to 10×10³/cm², and applyingpressure to the sheet to transfer the roughened pattern of the sheet androughen the surface of the support.

[0108] After the support has been roughened mechanically, it ispreferably dipped in an acid or an aqueous alkali solution in order toremove abrasives and aluminum dust, etc. which have been embedded in thesurface of the support. Examples of the acid include sulfuric acid,persulfuric acid, hydrofluoric acid, phosphoric acid, nitric acid andhydrochloric acid, and examples of the alkali include sodium hydroxideand potassium hydroxide. Among those mentioned above, an aqueous alkalisolution of for example, sodium hydroxide is preferably used. Thedissolution amount of aluminum in the support surface is preferably 0.5to 5 g/m². After the support has been dipped in the aqueous alkalisolution, it is preferable for the support to be dipped in an acid suchas phosphoric acid, nitric acid, sulfuric acid and chromic acid, or in amixed acid thereof, for neutralization.

[0109] Though there is no restriction for the electrolytic surfaceroughening method, a method in which the support is electrolyticallysurface roughened in an acidic electrolytic solution. Though an acidicelectrolytic solution generally used for the electrolytic surfaceroughening can be used, it is preferable to use an electrolytic solutionof hydrochloric acid or that of nitric acid. The electrolytic surfaceroughening method disclosed in Japanese Patent Publication No. 48-28123,British Patent No. 896,563 and Japanese Patent O.P.I. Publication No.53-67507 can be used. In the electrolytic surface roughening method,voltage applied is generally from 1 to 50 V, and preferably from 10 to30 V. The current density used can be selected from the range from 10 to200 A/dm², and is preferably from 50 to 150 A/dm². The quantity ofelectricity can be selected from the range of from 100 to 5000 C/dm²,and is preferably 100 to 2000 C/dm². The temperature during theelectrolytically surface roughening may be in the range of from 10 to50° C., and is preferably from 15 to 45° C.

[0110] When the support is electrolytically surface roughened by usingan electrolytic solution of nitric acid, voltage applied is generallyfrom 1 to 50 V, and preferably from 5 to 30 V. The current density usedcan be selected from the range from 10 to 200 A/dm², and is preferablyfrom 20 to 100 A/dm². The quantity of electricity can be selected fromthe range of from 100 to 5000 C/dm², and is preferably 100 to 2000C/dm². The temperature during the electrolytically surface rougheningmay be in the range of from 10 to 50° C., and is preferably from 15 to45° C. The nitric acid concentration in the electrolytic solution ispreferably from 0.1% by weight to 5% by weight. It is possible tooptionally add, to the electrolytic solution, nitrates, chlorides,amines, aldehydes, phosphoric acid, chromic acid, boric acid, aceticacid or oxalic acid.

[0111] When the support is electrolytically surface roughened by usingan electrolytic solution of hydrochloric acid, voltage applied isgenerally from 1 to 50 V, and preferably from 2 to 30 V. The currentdensity used can be selected from the range from 10 to 200 A/dm², and ispreferably from 50 to 150 A/dm². The quantity of electricity can beselected from the range of from 100 to 5000 C/dm², and is preferably 100to 2000 C/dm². The temperature during the electrolytically surfaceroughening may be in the range of from 10 to 50° C., and is preferablyfrom 15 to 45° C. The hydrochloric acid concentration in theelectrolytic solution is preferably from 0.1% by weight to 5% by weight.

[0112] After the support has been electrolytically surface roughened, itis preferably dipped in an acid or an aqueous alkali solution in orderto remove aluminum dust, etc. produced in the surface of the support.Examples of the acid include sulfuric acid, persulfuric acid,hydrofluoric acid, phosphoric acid, nitric acid and hydrochloric acid,and examples of the alkali include sodium hydroxide and potassiumhydroxide. Among those mentioned above, the aqueous alkali solution ispreferably used. The dissolution amount of aluminum in the supportsurface is preferably 0.5 to 5 g/m². After the support has been dippedin the aqueous alkali solution, it is preferable for the support to bedipped in an acid such as phosphoric acid, nitric acid, sulfuric acidand chromic acid, or in a mixed acid thereof, for neutralization.

[0113] The mechanical surface roughening and electrolytic surfaceroughening may be carried out singly, and the mechanical surfaceroughening followed by the electrolytic surface roughening may becarried out.

[0114] After the surface roughening, anodizing treatment may be carriedout. There is no restriction in particular for the method of anodizingtreatment used in the invention, and known methods can be used. Theanodizing treatment forms an anodization film on the surface of thesupport. For the anodizing treatment there is preferably used a methodof applying a current density of from 1 to 10 A/dm² to an aqueoussolution containing sulfuric acid and/or phosphoric acid in aconcentration of from 10 to 50%, as an electrolytic solution. However,it is also possible to use a method of applying a high current densityto sulfuric acid as described in U.S. Pat. No. 1,412,768, a method toelectrolytically etching the support in phosphoric acid as described inU.S. Pat. No. 3,511,661, or a method of employing a solution containingtwo or more kinds of chromic acid, oxalic acid, malonic acid, etc. Thecoated amount of the formed anodization film is suitably 1 to 50 mg/dm²,and preferably 10 to 40 mg/dm². The coated amount of the formedanodization film can be obtained from the weight difference between thealuminum plates before and after dissolution of the anodization film.The anodization film of the aluminum plate is dissolved employing forexample, an aqueous phosphoric acid chromic acid solution which isprepared by dissolving 35 ml of 85% by weight phosphoric acid and 20 gof chromium (IV) oxide in 1 liter of water.

[0115] The support which has been subjected to anodizing treatment isoptionally subjected to sealing treatment. For the sealing treatment, itis possible to use known methods using hot water, boiling water, steam,a sodium silicate solution, an aqueous dicromate solution, a nitritesolution and an ammonium acetate solution.

[0116] After the above treatment, the support is suitably undercoatedwith a water soluble resin such as polyvinyl phosphonic acid, a polymeror copolymer having a sulfonic acid in the side chain, or polyacrylicacid; a water soluble metal salt such as zinc borate; a yellow dye, anamine salt; and so on. The sol-gel treatment support, which has afunctional group capable of causing addition reaction by radicals as acovalent bond, is suitably used.

[0117] A method of forming an image on the light sensitive planographicprinting plate precursor of the invention comprises imagewise exposingthe light sensitive planographic printing plate precursor describedabove, and developing the exposed plate with a developer describedlater.

[0118] The light sources for forming an image on the light sensitiveplanographic printing plate precursor of the invention include, forexample, a laser, an emission diode, a xenon flush lamp, a halogen lamp,a carbon arc light, a metal halide lamp, a tungsten lamp, a highpressure mercury lamp, and a non-electrode light source.

[0119] When the light sensitive planographic printing plate precursor isimagewise exposed at one time, a mask material having a negative imagepattern made of a light shielding material is put on the plate to be inclose contact with the plate, and exposure is carried out through themask.

[0120] When an array light such as an emission diode array is used orexposure using a halogen lamp, a metal halide lamp or a tungsten lamp iscontrolled using an optical shutter material such as liquid crystal orPLZT, a digital exposure according to an image signal is possible andpreferable. In this case, direct writing is possible without using anymask material.

[0121] When a laser is used for exposure, which can be condensed in thebeam form, scanning exposure according to an image can be carried out,and direct writing is possible without using any mask material. When thelaser is employed for imagewise exposure, a highly dissolved image canbe obtained, since it is easy to condense its exposure spot in minutesize.

[0122] As the laser, argon laser, He-Ne gas laser, YAG laser orsemi-conductor laser is preferably used. In the invention, asemiconductor laser employing a InGaN type material, which cancontinuously emit light with a wavelength of from 380 to 430 nm, areespecially preferably used in markedly exhibiting the effects of theinvention.

[0123] A laser scanning method by means of a laser beam includes amethod of scanning on an outer surface of a cylinder, a method ofscanning on an inner surface of a cylinder and a method of scanning on aplane. In the method of scanning on an outer surface of a cylinder,laser beam exposure is conducted while a drum around which a recordingmaterial is wound is rotated, in which main scanning is represented bythe rotation of the drum, while sub-scanning is represented by themovement of the laser beam. In the method of scanning on an innersurface of a cylinder, a recording material is fixed on the innersurface of a drum, a laser beam is emitted from the inside, and mainscanning is carried out in the circumferential direction by rotating apart of or an entire part of an optical system, while sub-scanning iscarried out in the axial direction by moving straight a part of or anentire part of the optical system in parallel with a shaft of the drum.In the method of scanning on a plane, main scanning by means of a laserbeam is carried out through a combination of a polygon mirror, a galvanomirror and an Fθ lens, and sub-scanning is carried out by moving arecording medium. The method of scanning on an outer surface of acylinder and the method of scanning on an inner surface of a cylinderare more suitable for high density recording because they make it easyto enhance a precision of an optical system.

[0124] In the invention, the exposed light sensitive planographicprinting plate precursor is preferably subjected to heat treatmentbefore or during development. Such a heat treatment can improve adhesionbetween the support and the light sensitive photopolymerizable layer,and enhance the advantageous effects of the invention.

[0125] Regarding heat treatment, there is, for example, a developingmachine in which a preheating roller for preheating an exposedplanographic printing plate precursor to a predetermined temperature isarranged upstream a development section where the preheating is carriedout before development. The preheating roller is a roller comprised of apair of rollers, at least one of the pair of the rollers having aheating means within the roller. The roller having a heating means in itis a pipe of a metal with high thermal conductivity such as aluminum oriron, the pipe having a nichrome wire as a heating element. The outsidesurface of the pipe may be covered with a sheet of a plastic such aspolyethylene, polystyrene or Teflon. Details of such a preheating rollercan refer to Japanese Patent O.P.I. Publication No. 64-80962.

[0126] In the invention, it is preferred that the preheating is carriedout at 70 to 180° C. for 3 to 120 seconds.

[0127] The light sensitive planographic printing plate precursor used inthe invention is subjected to imagewise exposure to harden the exposedportions of the photopolymerizable light sensitive layer, and subjectedto developing treatment employing an alkaline developing solution toremove unexposed portions of the layer, whereby an image is formed. Asthe developer, a conventional alkali developer can be used. Examples ofthe developing solution include an alkali developing solution containinginorganic alkali agents such as sodium silicate, potassium silicate,ammonium silicate, sodium secondary phosphate, potassium secondaryphosphate, ammonium secondary phosphate, sodium bicarbonate, potassiumbicarbonate, ammonium bicarbonate, sodium carbonate, potassiumcarbonate, ammonium carbonate, sodium hydrogen carbonate, potassiumhydrogen carbonate, ammonium hydrogen carbonate, sodium borate,potassium borate, ammonium borate, sodium hydroxide, potassiumhydroxide, ammonium hydroxide, and lithium hydroxide.

[0128] The developing solution may contain organic alkali agents such asmonomethylamine, dimethylamine, trimethylamine, monoethylamine,diethylamine, triethylamine, monoisopropylamine, diisopropylamine,butylamine, monoethanolamine, diethanolamine, triethanolamine,monoisopropanolamine, diisopropanolamine, ethyleneimine,ethylenediamine, and pyridine.

[0129] These alkali agents can be used singly or in combination of twoor more kinds thereof. The developing solution may optionally contain asurfactant such as an anionic surfactant, an amphoteric surfactant oralcohol.

[0130] The developer in the invention is preferably an aqueous solution,which has a silicate concentration of 1.0% by weight in terms of SiO₂,and has a pH of from 8.5 to 12.5. The aqueous solution may contain otheradditives. It is preferred that the aqueous solution further contains asurfactant in an amount of from 0.1 to 5.0% by weight. It is alsopreferred that the aqueous solution further contains the componentsdescribed in the developing solution above.

EXAMPLES

[0131] Next, synthetic examples, manufacturing examples of support, andexamples will be shown below, but the present invention is not limitedthereto. In the examples, “parts” represents “parts by weight”, unlessotherwise specified.

Example 1

[0132] <<Synthesis of Polymer Binder, Acryl Copolymer 1>>

[0133] Thirty parts of methacrylic acid, 50 parts of methylmethacrylate, 10 parts of acrylonitrile, 10 parts of ethyl methacrylate,500 parts of ethanol, and 3 parts of α,α∝-azobisisobutylonitrile wereput in a three neck flask under nitrogen atmosphere, and reacted undernitrogen atmosphere for 6 hours at 80° C. in an oil bath. After that,the reaction mixture was refluxed at a boiling point of isopropylalcohol for one hour, and 3 parts of triethylbenzylammonium chloride and25 parts of glycidyl methacrylate were further added to the mixture, andreacted for additional 3 hours. Thus, acryl copolymer 1 was obtained.The weight average molecular weight of the acryl copolymer 1 was 35,000,measured according to GPC. The glass transition temperature Tg of theacryl copolymer 1 was 85° C., measured according to DSC (differentialthermal analysis). The mixture was heated to 160° C. for 3 hours toobtain a solid. The solid content of the mixture was 20% by weight,which was obtained from the weight of the resulting solid.

[0134] <<Preparation of Light Sensitive Planographic Printing PlatePrecursor Sample>>

[0135] (Preparation of Support)

[0136] A 0.24 mm thick aluminum plate (material 1050, quality H16) wasdegreased at 60° C. for one minute in a 5% sodium hydroxide solution,washed with water, immersed at 25° C. for one minute in a 10%hydrochloric acid solution to neutralize, and then washed with water.The resulting aluminum plate was electrolytically etched using analternating current at 25° C. for 60 seconds at a current density of 100A/dm² in a 0.3 weight % nitric acid solution, and desmutted at 60° C.for 10 seconds in a 5% sodium hydroxide solution. The desmutted aluminumplate was anodized at 25° C. for 1 minute at a current density of 10A/dm² and at a voltage of 15 V in a 15% sulfuric acid solution, andsubjected to hydrophilic treatment at 75° C., employing a 1% polyvinylphosphonic acid aqueous solution. Thus, support was obtained. The centerline average surface roughness (Ra) of the support was 0.65 μm.

[0137] (Preparation of Subbed Support)

[0138] The following subbing layer coating liquid was coated on thesupport obtained above using a wire bar, dried at 90° C. for one minute,and further heated at 110° C. for 3 minutes to give a subbing layer witha dry thickness of 0.1 g/m². Thus, a subbed support was obtained.<Subbing layer coating liquid> γ-Methacryloxypropyltrimethoxysilane  1part Methyl ethyl ketone 80 parts Cyclohexanone 19 parts

[0139] The following photopolymerizable light sensitive layer coatingliquid 1 was coated on the subbed support using a wire bar, and dried at95° C. for 1.5 minutes to give a photopolymerizable light sensitivelayer with a dry thickness of 1.4 g/m². After that, the following oxygenshielding layer coating liquid was coated on the photopolymerizablelight sensitive layer using an applicator, and dried at 75° C. for 1.5minutes to give an oxygen shielding layer with a dry thickness of 1.8g/m². Thus, light sensitive planographic printing plate precursorsamples 1 through 15 were prepared. (Photopolymerizable light sensitivelayer coating liquid 1) Acryl copolymer 1 40.0 parts Spectralsensitizing dye 1 1.0 part Spectral sensitizing dye 2 1.0 part IRGACURE784 (produced by 4.0 parts Ciba Specialty Chemicals Co.) N-phenylglycinebenzyl ester 4.0 parts Triazine (as shown in Table 1) 1.0 part Additionpolymerizable ethylenically 20.0 parts unsaturated bond-containingmonomer (as shown in Table 1) NK OLIGOU-4HA (Urethane tipe monomer 10.0parts produced by Shinnakamura Chemical Co., Ltd.) NK ESTER-4G(Tetraethylene glycol 10.0 parts dimethacrylate produced by ShinnakamuraChemical Co., Ltd.) Phthalocyanine pigment 6.0 parts (MHI 454 producedby Mikuni Sikisosha) 2-t-Butyl-t-(3-t-butyl-2-hydroxy- 0.5 parts5-methylbenzyl)-4- methylphenyl acrylate (Sumirizer GS produced bySumitomo 3M Co., Ltd.) Fluorine-contained surfactant 0.5 parts (FC-178Kproduced by Dainippon ink Kagaku Kogyo Co., Ltd.) Methyl ethyl ketone 80parts Cyclohexanone 820 parts Spectral sensitizing dye 1

Spectral sensitizing dye 2

[0140] <Oxygen shielding layer coating liquid> Polyvinyl alcohol (GL-05,produced 89 parts by Nippon Gosel Kagaku Co., Ltd.) Water solublepolyamide (P-70, 10 parts produced by Toray Co., Ltd.) Surfactant(Surfinol 465, 0.5 parts produced by Nisshin Kagaku Kogyo Co., Ltd.)Water 900 parts

[0141] <<Evaluation of Light Sensitive Planographic Printing PlatePrecursor Sample>>

[0142] Sensitivity

[0143] The light sensitive planographic printing plate precursor sampleobtained above was imagewise exposed at a resolving degree of 2400 dpi,employing a plate setter Tiger Cat (produced by ECRM Co., Ltd.) equippedwith a light source emitting light with a wavelength of 532 nm. Herein,dpi represents the dot numbers per 2.54 cm. The image pattern used forexposure comprised a solid image and a square dot image with a screennumber of 175 LPI and a 50% dot area. Subsequently, the exposed samplewas subjected to development treatment employing a CTP automaticdeveloping machine (PHW 23-V produced by Technigraph Co., Ltd.) toobtain a planographic printing plate. Herein, the developing machinecomprised a preheating section for preheating the exposed sample at 105°C. for 10 seconds, a pre-washing section for removing the oxygenshielding layer before development, a development section charged withdeveloper having the following developer composition, a washing sectionfor removing the developer remaining on the developed sample afterdevelopment, and a gumming section charged with a gumming solution (asolution obtained by diluting GW-3, produced by Mitsubishi Chemical Co.,Ltd., with water by a factor of 2) for protecting the surface of thedeveloped sample. Thus, planographic printing plate samples 1 through 13were obtained.

[0144] The lowest exposure energy amount (μJ/cm²) capable of reproducingthe solid image above in the resulting planographic printing platewithout reduction of the layer thickness at image portions was definedas sensitivity 1. The less the lowest exposure energy amount (μJ/cm²)is, the higher the sensitivity. <Composition of developer> Potassiumsilicate A 8.0% by weight (an aqueous potassium silicate solutioncontaining 25.5-27.5% by weight of SiO₂ and 12.5-14.5% by weight of K₂O)NEWCOL B-13 (produced 3.0% by weight by Nippon Nyukazai Co., Ltd.)Potassium hydroxide Amount giving pH 12.3

[0145] Storage Stability (Sensitivity Stability)

[0146] The light sensitive planographic printing plate precursor sampleobtained above was packaged in a light shielding and moisture-proofingpackage. The resulting package was stored at 55° C. for 8 hours, thencooled to 5° C. and stored at that temperature for 16 hours. Thisoperation was repeated three times. Sensitivity of the resulting samplewas measured in the same manner as above as sensitivity 2. Sensitivitydifference {Sensitivity 2-Sensitivity 1 (μJ/cm²)} was calculated as anevaluation measure of storage stability. The less sensitivity differenceshows more excellent storage stability.

[0147] Printing Durability

[0148] The above obtained light sensitive planographic printing platesample was exposed through an original with a screen line number of 175at an optimal exposure amount, and developed in the same manner as aboveto obtain a planographic printing plate. Employing the resultingprinting plate, printing was carried out on a press (DAIYA1F-1 producedby Mitsubishi Jukogyo Co., Ltd.), wherein a coat paper, printing ink(soybean oil-based ink “Naturalist 100” produced by Dainippon Ink KagakuKogyo Co., Ltd.), and dampening water (SG-51, H solution produced byTokyo Ink Co., Ltd., Concentration: 1.5%) were used. The number ofprints printed from the beginning of the printing till when dotreduction at highlight image portions was observed was counted as anevaluation measure of storage stability.

[0149] The results are shown in Table 1. TABLE 1 Printing Sensi- Sensi-Storage Durability Sample Mono- Triazine tivity 1 tivity 2 stability(print No. mer compound (μJ/cm²) (μJ/cm²) (μJ/cm²) number) Remarks 1 M-1TA-7 80 90 10 ≧300,000 Inv. 2 M-2 TA-7 80 100 20 ≧300,000 Inv. 3 M-3TA-7 120 130 10 ≧300,000 Inv. 4 M-4 TA-7 80 110 30 ≧300,000 Inv. 5 M-6TA-7 60 80 20 ≧300,000 Inv. 6 N-6 TA-7 100 100 0 ≧300,000 Inv. 7 M-7TA-7 120 130 10 ≧300,000 Inv. 8 M-2 TB-12 90 100 10 ≧300,000 Inv. 9 M-3TB-12 120 130 10 ≧300,000 Inv. 10 M-4 TB-12 90 110 20 ≧300,000 Inv. 11M-2 None 120 150 30 250,000 Inv. 12 M-3 None 150 180 30 250,000 Inv. 13M-4 None 120 160 40 250,000 Inv. 14 *Mono- TA-7 180 260 80 170,000 Comp.mer A 15 *Mono- None 250 400 150 140,000 Comp. mer A

[0150] As is apparent from Table 2 above, inventive samples comprisingthe addition polymerizable ethylenically double bond-containing monomerfalling within the scope of the invention provide high sensitivity to532 nm light, high storage stability and high printing durability ascompared with comparative samples.

Example 2

[0151] Light sensitive planographic printing plate precursor samples 21through 27 were prepared in the same manner as in Example 1 above,except that the following photopolymerizable light sensitive layercoating liquid 2 was used instead of the photopolymerizable lightsensitive layer coating liquid 1 (Photopolymerizable light sensitivelayer coating liquid 2) Acryl copolymer 1 40.0 parts Spectralsensitizing dye 3 1.0 part Spectral sensitizing dye 4 1.0 part Spectralsensitizing dye 5 1.0 part Tetrabutylammonium butyl trinaphthyl 4.0parts Borate Triazine (as shown in Table 2) 1.0 part Additionpolymerizable ethylenically 20.0 parts unsaturated bond-containingmonomer (as shown in Table 2) NK OLICOU-4HA (produced by 10.0 partsShinnakamura Chemical Co., Ltd.) NK ESTER-4G (produced by 10.0 partsShinnakamura Chemical Co., Ltd.) Phthalocyanine pigment 6.0 parts (MHI454 produced by Mikuni Sikisosha) 2-t-Butyl-6-(3-t-butyl-2-hydroxy- 0.5parts 5-methylbenzyl)-4- methylphenyl acrylate (Sumirizer GS produced bySumitomo 3M Co., Ltd.) Fluorine-contained surfactant 0.5 parts (FC-178Kproduced by Dainippon ink Kagaku Kogyo Co., Ltd.) Methyl ethyl ketone 80parts Cyclohexanone 820 parts Spectral sensitizing dye 3

Spectral sensitizing dye 4

Spectral sensitizing dye 5

[0152] <<Evaluation of Light Sensitive Planographic Printing PlatePrecursor Samples 21-27>>

[0153] The light sensitive planographic printing plate precursor sampleobtained above was imagewise exposed at a resolving degree of 2400 dpi,employing a modified plate setter of a plate setter Tiger Cat (producedby ECRM Co., Ltd.) equipped with a laser with an output power of 30 mWemitting light with a wavelength of 408 nm. Subsequently, the exposedsample was processed and evaluated for sensitivity, storage stabilityand printing durability in the same manner as in Example 1.

[0154] The results are shown in Table 2. TABLE 2 Printing Sensi- Sensi-Storage Durability Sample Mono- Triazine tivity 1 tivity 2 stability(print No. mer compound (μJ/cm²) (μJ/cm²) (μJ/cm²) number) Remarks 21M-2 TA-7 30 35 5 ≧300,000 Inv. 22 M-3 TA-7 30 35 5 ≧300,000 Inv. 23 M-4TA-7 40 40 0 ≧300,000 Inv. 24 M-3 TA-12 25 30 5 ≧300,000 Inv. 25 M-4TA-12 30 35 5 ≧300,000 Inv. 26 M-4 TA-12 35 40 5 ≧300,000 Inv. 27 *Mono-TA-7 40 65 25 150,000 Comp. mer A

[0155] As is apparent from Table 2 above, inventive samples comprisingthe addition polymerizable ethylenically double bond-containing monomerfalling within the scope of the invention provide high sensitivity to408 nm light, high storage stability and high printing durability ascompared with comparative samples.

EFFECT OF THE INVENTION

[0156] The present invention provides a light sensitive composition anda light sensitive planographic printing plate precursor, each providinghigh sensitivity, high storage stability, and high printing durability.

What is claimed is:
 1. A light sensitive composition containing A) anaddition polymerizable ethylenically double bond-containing monomer, B)a photopolymerization initiator, and C) a polymer binder, wherein theaddition polymerizable ethylenically double bond-containing monomer is areaction product of a tertiary amine having two or more hydroxyl groupsin the molecule, a diisocyanate having an aromatic ring in the moleculeand a compound having a hydroxyl group and an addition polymerizableethylenically double bond in the molecule.
 2. The light sensitivecomposition of claim 1, wherein the photopolymerization initiator is apolyhalogenated methyl group-containing triazine compound.
 3. The lightsensitive composition of claim 1, wherein the tertiary amine has ahydroxyl group of from 2 to 6 in the molecule.
 4. The light sensitivecomposition of claim 1, wherein the polymer binder is a copolymer of acarboxyl group-containing monomer and an alkyl methacrylate or alkylacrylate.
 5. The light sensitive composition of claim 4, wherein thecarboxyl group-containing monomer is acrylic acid or methacrylic acid.6. A light sensitive planographic printing plate precursor comprising asupport and provided thereon, a photopolymerizable light sensitive layercontaining A) an addition polymerizable ethylenically doublebond-containing monomer, B) a photopolymerization initiator, and C) apolymer binder, wherein the addition polymerizable ethylenically doublebond-containing monomer is a reaction product of a tertiary amine havingtwo or more hydroxyl groups in the molecule, a diisocyanate having anaromatic ring in the molecule and a compound having a hydroxyl group andan addition polymerizable ethylenically double bond in the molecule. 7.The light sensitive planographic printing plate precursor of claim 6,wherein the photopolymerization initiator is a polyhalogenated methylgroup-containing triazine compound.
 8. The light sensitive planographicprinting plate precursor of claim 6, wherein the tertiary amine has ahydroxyl group of from 2 to 6 in the molecule.
 9. The light sensitiveplanographic printing plate precursor of claim 6, wherein the polymerbinder is a copolymer of a carboxyl group-containing monomer and analkyl methacrylate or alkyl acrylate.
 10. The light sensitiveplanographic printing plate precursor of claim 6, wherein the carboxylgroup-containing monomer is acrylic acid or methacrylic acid.